out board power for an Oday 25
- Thread starter bruce tamlyn
- Start date
last season, my old Honda 100, overheated, due to a crusted up water pump housing. Took way too long to get parts, so I bought a new Mercury 8 hp electric start long shaft model. I only bought the electric start because they did not have the plain rope start in stock. This motor is fantastic! Plenty of power and the electric start is so convenient. I highly recommend it.
Since the two stroke vs. four stroke issue has now been decided by the manufacturers for all of us, the most important factor left to decide is the length of the shaft. IMHO, I would buy the outboard with the longest shaft I could find. The "standard" length for Long shaft models tends to be 20", although there is at least one manufacturer (Nissan/Tohatsu) that offers an extra long shaft at 25". If you've ever dealt with the cavitation you get even with a long shaft model, you would never question the idea of a deeper prop.
And if you are replacing an older two stroke engine with a four stroke for the first time, remember to make sure your transom mounting bracket can handle four stroke engines. Its not just the added weight of a four stroke that needs to be accommodated; the four stroke generates more torque than the two stroke. There are lots of threads on this subject here and on other sites discussing the balance among weight, horsepower and torque between two and four stroke engines. I'm no engineer, but you need to seriously consider if you need a new transom mount to go with your new engine.
And if you are replacing an older two stroke engine with a four stroke for the first time, remember to make sure your transom mounting bracket can handle four stroke engines. Its not just the added weight of a four stroke that needs to be accommodated; the four stroke generates more torque than the two stroke. There are lots of threads on this subject here and on other sites discussing the balance among weight, horsepower and torque between two and four stroke engines. I'm no engineer, but you need to seriously consider if you need a new transom mount to go with your new engine.
If you need a new motor mount, Garhauer makes a really nice stainless steel version. Sage Marine is spec'ing them on the Sage 17, checked it out in Annapolis this past fall.
Also, keep in mind that most small outboard props are pitched for running small jon boats at speed. This is not what we do with our displacement sailboats. Two ways you can attack it are to go with a "sail pro" model, from Nissan/Tohatsu/Mercury, which have a 25" shaft, alternator, generally starting around 9hp, and include a high thrust prop. Alternately, pick the motor you like and plan to get a high thrust prop for it. Sometimes, that means larger diameter prop, sometimes that means lower pitch prop, and sometimes it means a 4 blade "Mickey Mouse ear" prop. It all depends on what the manufacturer has for the model of outboard you have. A higher thrust prop gives you more control at low speeds.
Also, keep in mind that most small outboard props are pitched for running small jon boats at speed. This is not what we do with our displacement sailboats. Two ways you can attack it are to go with a "sail pro" model, from Nissan/Tohatsu/Mercury, which have a 25" shaft, alternator, generally starting around 9hp, and include a high thrust prop. Alternately, pick the motor you like and plan to get a high thrust prop for it. Sometimes, that means larger diameter prop, sometimes that means lower pitch prop, and sometimes it means a 4 blade "Mickey Mouse ear" prop. It all depends on what the manufacturer has for the model of outboard you have. A higher thrust prop gives you more control at low speeds.
As Brian said, look for a "High Thrust" model outboard and 25" extra long shaft. He mentioned Tohatsu/Nisson/ Mercury. Also look at a Yamaha. The Yamaha T9.9 is a high thrust outboard and is available in the extra long shaft.
What I like about the Yamaha is that the gear shift is on the OB tiller, just behind the throttle twist grip. This brings it up to an easy reach compared to the shifter on the front of the motor. Not sure what other motors have a shifter on the tiller but I am pretty sure the Tohatsu line does not. That is the main reason I went with the Yamaha.
A 9.9 may be more power than you need but in that size range you can get the electric start, charging and a really nice option is power tilt.
We needed a new OB last summer for our 25 and the power tilt was the only one available. We went with it and I am glad we did. The admiral could not work the manual tilt and bracket but now she can lower the OB and start it on her own. Nice safety feature in the event I am disabled or in the water.
What I like about the Yamaha is that the gear shift is on the OB tiller, just behind the throttle twist grip. This brings it up to an easy reach compared to the shifter on the front of the motor. Not sure what other motors have a shifter on the tiller but I am pretty sure the Tohatsu line does not. That is the main reason I went with the Yamaha.
A 9.9 may be more power than you need but in that size range you can get the electric start, charging and a really nice option is power tilt.
We needed a new OB last summer for our 25 and the power tilt was the only one available. We went with it and I am glad we did. The admiral could not work the manual tilt and bracket but now she can lower the OB and start it on her own. Nice safety feature in the event I am disabled or in the water.
I believe the Merc 8HP and 9.9hp have eliminated the shift lever and integrate the shifting into the twist-grip (from neutral, you twist one way for forward and the other for reverse) users report that it works well once you become acustomed to it. The Merc 9.9 is available in 15", 20" and 25" mosdels (25" is "Sail-Power") but 8 HP is only available in 15" and 20" shaft. Evinrude has a 9.8HP 4-stroke with an available 25" shaft, Suzuki is the same (they make the 3.5hp, 4 hp, 6 HP, 9.8 HP, and 15HP for Evinrude, all are 4-stroke. Evinrude also makes the HO 15HP ETEC, but that is a heavy, 177# detuned 25 HP)
25" shaft is a big advantage on boats like the 25.
25" shaft is a big advantage on boats like the 25.
My 25 came with a 2001 T9.9 so I am guessing the mount was added at the same time. I have seen at least one other 25 with the same bracket, a OMC bracket, installed the same way.
The backing plates, both in and out, look to be 1/2" or 5/8" starboard. Adjustments in the bracket and OB allow the motor to be trimmed properly. The lack of any gel coat checking or cracking around the area indicates to me that there is no flexing and the mount is holding up well.
As a side note, the 2001 T9.9 had an electric choke which was a PIA so when it began having problems we replaced it. I looked at some other OBs but went with another Yamaha T9.9 which now has a manual choke.
Attached are a couple of photos.
The backing plates, both in and out, look to be 1/2" or 5/8" starboard. Adjustments in the bracket and OB allow the motor to be trimmed properly. The lack of any gel coat checking or cracking around the area indicates to me that there is no flexing and the mount is holding up well.
As a side note, the 2001 T9.9 had an electric choke which was a PIA so when it began having problems we replaced it. I looked at some other OBs but went with another Yamaha T9.9 which now has a manual choke.
Attached are a couple of photos.
Attachments
![20130723_123432[1].jpg](/data/attachments/54/54717-ed07e138bf2fc8ced9a7421864bead9b.jpg)
My 1983 O'Day 25 has the motor mount on the other side. There is a wedge between the transom and the bracket. Were you able to match the wedge bolt holes with the bracket?